Abstract

For low average power applications, Yb-sensitized Er lasers operating at 1.5 microns work well in phosphate glasses.^1,2 This is because of the slightly exothermic near resonance between the P-O stretch overtone absorption at 3 000 cm⁻¹ (3.3 microns) and the Er^{3+ 4}I_11/2 -> ⁴I₁₃/₂ emission at 3 400 cm⁻¹ which causes selective deactivation of the ⁴I_11/2 level. A short ⁴I_11/2 lifetime is important because it transforms the otherwise reversible Yb³⁺ -> Er³⁺ energy transfer process into an irreversible one.

© 1994 Optical Society of America